The design and construction of the filling section of the volumetric filling machines varies between two extremes-machines that fill exact amounts of products, and machines that fill products within a small tolerance. Control of the product between these two extremes will vary with each particular machine that is made. However, each machine has its own particular application for which it functions the best.

Gravity filling is the simplest filling method. The uncomplicated construction and operation of gravity filling machines permits them to run with a minimum of maintenance. The supply tank (more properly called the filler bowl) is the upper, central part of the machine. Filling stems are attached to the bottom surface of the bowl at each container filling point.

The methods and equipment used to fill bottles vary with each application in which they are used. In some cases, the filling machines are simple in design, construction, and operation. In other cases, the equipment is more complicated, operate at fast speeds, and handle many different sizes and shapes of bottles. One of the most important aspects in choosing the right filling equipment is the product being placed in the container.